Structure and properties of egg white protein films modified by high-intensity ultrasound: An effective strategy

Edible films based on egg white protein (EWP) were prepared, and it were modified by high-intensity ultrasound (HIUS) to improve the functional properties. The findings indicated the properties of EWP films were improved at the appropriate time of HIUS treatment. With the increase of ultrasonic time, water vapor permeability (WVP) and tensile strength (TS) of EWP films ascended and then declined, and the best performance (3.30 g·mm/ m2·h·KPa for WVP, and 7.28 MPa for TS) was achieved when ultrasonic time was 10 min. Thermogravimetric analysis exhibited ultrasound could enhance the thermal stability of EWP films. The SEM reflected moderate ultrasonic treatment could make the EWP films smoother. The FTIR spectroscopy and X-ray diffraction patterns of EWP films were changed by HIUS, which illustrated the secondary structure of the protein was altered. The transverse relaxation curve obtained by LF-NMR analysis showed the tightness between water and the films.